1. Field of the Invention
The present invention relates to a backlight module. More particularly, the present invention relates to a backlight module including an independent light source.
2. Description of Related Art
Generally, a conventional flat panel display device such as liquid crystal display (LCD) is a non-self-illuminant display. Therefore, a conventional LCD requires a device functioning as a light source, to provide planar or linear light, and this device is usually called a backlight module. Backlight modules are generally classified into two types, in which one is a direct type and the other is a side-edge type. The component of a conventional direct type backlight module includes, for example, lamp tubes such as cold cathode tubes, a diffusion sheet and a prism sheet. However, in order to provide uniform, planar light for the LCD, the intervals between the lamp tubes, and the distance between the lamp tubes and the diffusion sheet/prism sheet have to be precisely controlled to avoid non-uniform distribution of light. In addition, minimization of the thickness of the backlight module is limited by the distance between the lamp tubes and the diffusion sheet.
In a side-edge type backlight module, the light from the lamp tubes is introduced into a light guide plate to spread the light. Therefore, the thickness of the backlight module can be further minimized. However, the distribution of the planar light emitted from the side-edge type backlight module is still non-uniform. Moreover, it is still hard to enlarge the size of the side-edge type backlight module. In addition, the components of the two conventional backlight modules described above are complex. Accordingly, minimization of the thickness of the conventional backlight modules is a problem to be solved.
Furthermore, the two conventional backlight modules generate a lot of heat in operation. However, a normal operation of LCD requires a small and stable temperature range. Accordingly, heat dissipation of the conventional backlight modules is another problem to be solved.
Therefore, the U.S. Pat. No. 6,655,825 discloses a white backlight device of an LCD for solving the problems described above, wherein a light mixing optical fiber is provided for mixing red, green and blue light into a white light, and then the white light is introduced to a side edge of the light guide plate by using a light disperser, and the white light is projected to the LCD by the light guide plate. However, operation of the present backlight module is also classified into conventional side-edge type backlight module, thus it is hard to enlarge the size of the backlight module.